Arthroscopic joint surgery is one of the most commonly performed procedures in surgical practice and its use is steadily increasing. For example, more than 2 million arthroscopic procedures were performed in the United States in 2003, and that number is steadily increasing. In Canada, thousands of arthroscopic procedures are performed every year with some procedures being performed completely arthroscopically as opposed to traditional open approaches.
One major advantage of arthroscopic surgery is its minimal invasive fashion which limits surgical wounds, bleeding, and in particular, limits post-operative pain and recovery time. During arthroscopy, irrigating solutions are used to distend and flush the joint. Two of the most commonly used irrigating solutions are saline and Ringer's lactate. Despite the relative safety of their use intra-vascularly, the short and long term effects and relative safety of their use in other environments is unclear. Furthermore the prolonged bathing of articular tissue in these foreign environments is unclear. In fact, there is mounting evidence that commonly used fluids and drugs given intra-articularly may be detrimental to joint tissue viability.
For example, in an effort to improve post-operative pain control and limit systemic side effects, the use of intra-articular local anesthetics (e.g. bupivacaine, xylocaine, ropivicaine) has gained popularity. Local anesthetic use following arthroscopic surgery is routinely performed as a single dose intra-articular injection. Furthermore, to provide even longer term relief, continuous infusion of intra-articular local anesthetics is commonly performed for up to 48-72 hours.
However, a number of recent in vitro studies have demonstrated that local anesthetics are, in fact, highly toxic to articular tissues. For example, several studies have documented that exposure to local anesthetics decreased cellular viability of articular tissues in a dose and duration dependent manner. Additionally, many have reported acute chondrolysis (i.e. cartilage cell death and loss of tissue integrity) following prolonged intra-articular local anesthetic infiltration.
During the course of arthroscopic surgery, it is common to use electrical cauterization and, or mechanical drilling, burring, or grinding to effect changes to the tissue. These procedures generate excessive heat that can lead to collateral morbidity to the cells and tissues near the site of repair. In addition, the instruments used during an arthroscopic procedure can impact and cut the articular cartilage, insults that have been linked to chondrocyte death (Am J Sports Med 2009, 37: 2318-23).
Our studies have investigated the effects of irrigant fluids (e.g saline, ringers lactate) on tissue viability (FIG. 1, See Appendix). The effects of irrigant fluids on tissue viability has also been investigated. Studies using both in vitro and in vivo animal models, have demonstrated detrimental effects of non-physiologic fluids (e.g. normal saline, ringers lactate) on cartilage morphology, ultrastructure, metabolism, and biomechanics (J Bone Joint Surg Am 1983, June 65(5):629-3). Based on this data there is an ongoing need to develop a physiologic solution applicable to medical and veterinary surgical needs that can ameliorate the problem of tissue destruction resulting from the detrimental effects of non-physiologic surgical adjuvants and irrigants, as well as the collateral mechanical and thermal damage associated with surgical intervention.